The present invention relates to a charger, in particular an exhaust gas turbocharger, for a drive device, having a compressor that is capable of being electrically supported or driven by a media gap motor, the media gap motor having a rotor that is operatively connected to a bearing shaft of a compressor impeller of the compressor, as well as a stator that surrounds the rotor at least in some regions in the circumferential direction, relative to an axis of rotation of the bearing shaft. In addition, the present invention relates to a drive device.
The charger can be a component of the drive device. The drive device is for example allocated to a motor vehicle, and is used to drive the motor vehicle. The drive device has for example a drive aggregate, in particular an internal combustion engine. In addition, the charger is allocated to the drive device. Using the charger, air is compressed, in particular fresh air that is supplied to the drive device, and in this way the air is brought from a lower, first pressure level to a higher, second pressure level. After the compression of the air by the charger, or with the aid of the compressor of the charger, the air is supplied to the drive aggregate. In this way, the efficiency and/or performance of the drive aggregate can be improved.
If the charger is fashioned as an exhaust gas turbocharger, then in addition to the compressor it has a turbine over, or through, which exhaust gas flows during operation of the drive device. The exhaust gas is for example produced by the drive aggregate, thus in particular by the internal combustion engine. When flowing through the turbine, enthalpy and/or flow energy is taken from the exhaust gas and is converted into kinetic energy that is then used to drive the compressor. Correspondingly, the charger, and in particular the pressure ratio that can be reached using the charger, i.e. the ratio between the second pressure level and the first pressure level, is to a large extent a function of an operating point of the drive device.
For this reason, the media gap motor is allocated to the charger. With the aid of this motor, the compressor can be electrically supported. The compressor can also be driven solely by the media gap motor. For this purpose, the media gap motor is operatively connected to the bearing shaft of the compressor impeller of the compressor, so that, using the media gap motor, a torque can be applied to the bearing shaft and thus to the compressor impeller, which is rigidly and/or permanently operatively connected to the bearing shaft. In addition to the rotor, the media gap motor has the stator, which surrounds the rotor at least in some regions, in particular in the circumferential direction relative to the axis of rotation of the bearing shaft, or of the compressor impeller.
The media gap motor is distinguished in that it has a very large air gap between the stator and the rotor. For example, an outer diameter of the rotor is at most 50% relative to an inner diameter of the stator. The region between the outer circumference of the rotor and the inner circumference of the stator is designated the air gap. Due to the very large air gap, compared to conventional electric motors, comparatively large stator coils having high inductance are required. This inductance causes high apparent currents that can cause electrical losses both in the coils and in a power electronics of the media gap motor, for example in the form of heat.
The publication “Hybridturbolader mit neuer Elektromotorentechnik [Hybrid turbocharger having new electric motor technology],” MTZ, March 2014, pp. 50-55, describes a hybrid turbocharger.